The present invention relates to a robot hand for grasping objects and, more particularly, to a robot hand including optical approach sensing elements for detecting the distance between the robot hand and the object to be picked up.
Industrial robot hands or manipulators are currently being introduced into various industrial fields. These robot hands result in production efficiencies as well as significant cost savings. In such industrial applications, robot hands which can pick up objects and transfer them to a predetermined position are essential.
However, presently available robot hands which have been adapted for picking up objects have proven inadequate for most industrial applications. As an example, many presently available robot hands are adapted for picking up objects which are arranged in a predetermined position, e.g., occur at regular intervals along a conveyor which moves at a constant speed. Such devices incur difficulties maintaining synchronism with the series of objects. Further, difficulties are encountered when one or several objects have been misplaced.
Other presently available robotic hands employ complicated visual recognition systems for determining the position of objects to be picked up. These systems generally include sophisticated information processing circuitry for processing the massive amount of data necessary for visual recognition. These systems are typically very high in cost, and, therefore, impractical for most industrial applications.
Still other robot hands have been provided with a plurality of light emitting devices for generating a plurality of light beams such that the hand is capable of picking up an object when the center of the object is not located preciselsy at the prescribed position. Such a robot hand has been disclosed in U.S. Pat. No. 4,423,998, issued Jan. 3, 1984, to Hajimu Inaba et al. This system, however, is not capable of detecting the distance between the robot hand and the object to be picked up. Also, this system is unable to detect objects which may provide an obstacle to movement of the robot hand.
It is, therefore, desirable to provide a robot hand which is capable of picking up objects. It is further desirable to provide a robot hand which is capable of picking up objects whether or not the object is located at a predetermined position. Similarly, it is desirable to provide a robot hand which is capable of determining the distance between the robot hand and an object which is to be picked up. It is also desirable to provide a robot hand which is capable of determining the distance between the robot hand and other objects within the immediate vicinity of the robot hand. As always, it is desirable to provide such a robot hand without employing expensive electronic circuitry.